In U.K. Patent Applications Nos. 31366/75 and 41136/76 we describe moulding compositions comprising thermoplastics materials, a reinforcing filler which is either glass fibres or mica, and a minor proportion of a polyimide prepolymer, which is capable of thermosetting. The polyimide prepolymers concerned are addition polymers and their preparation is described in U.K. Pat. Nos. 1,190,718; 1,355,401; 1,355,402; 1,355,403; 1,355,405; 1,355,406 and 1,355,407.
The effect of the polyimide prepolymers in these compositions is to increase strength and impact resistance of mouldings produced therefrom.
U.S. Pat. No. 3,717,615 discloses polymer compositions based on a mixture of a mono-imide of specified general formula and a bis-imide of specified general formula. It also discloses that the mono- and bis-imides can be co-reacted with various thermoplastics during copolymerization of the imides and that the resulting compositions may be compounded with fillers including glass fibre, and with synthetic rubbers. The polyimides prepared in this specification are, however, the basis of the compositions described, and the final product in each case is a thermoset material. Where thermoplastics materials are used, their proportion is less than that of the mixture of imides and they are co-reacted in the polymerization of the imides.
U.S. Pat. No. 3,678,015 discloses reacting an organic diamine with an aliphatically unsaturated dicarbonyl reagent in a solvent system to produce a polyimide by a condensation reaction. The polyimide is said to be able to be employed in combination with various thermoplastics polymers and can be compounded with fillers including glass fibre. The compositions disclosed are thermosetting, and the polyimide is not an addition polymer, nor is the inclusion of rubbery polymers in the compositions disclosed.